1. Field of the Invention
This invention relates to solar collector systems and, more specifically, relates to such systems employing particulate energy collecting media.
2. Description of the Prior Art
Various means for attempting to make use of solar energy have been known. As in recent years, the world has experienced a diminished supply of energy resources, solar systems which dependably, economically and efficiently make use of solar energy have been needed.
In general, known solar energy systems employ air, water or an aqueous solution as the means for absorbing solar energy and subsequently through means of a heat exchanger, delivering the absorbed solar heat to a different medium. Frequently, the air or water which absorbs heat directly from exposure to solar radiation, by means of a heat exchanger, delivers the heat to a storage medium with the ultimate heat receiving zone receiving heat from the storage medium.
Among the problems encountered with the water or aqueous solution heat collectors are freezing, evaporation, condensation, and undesired leakage resulting in damage to the building and its contents. Any of these undesired events can result in failure of the system, or at minimum, substantially reduced efficiency. Among the problems with air systems are inefficient heat transfer between the solar collector and the air and between the air and the energy storage medium.
It has been suggested to employ an endless belt which is adapted to, in one zone, receive energy from exposure to solar radiation and, in another zone, to transfer the heat to either air or water which is disposed in an adjacent chamber. In such a system the belt serves as the collector medium and the air or water as the storage medium. See U.S. Pat. No. 3,972,316.
U.S. Pat. No. 4,077,849 is directed toward the use of solar energy in desalination apparatus. It discloses the use of metal balls or cylindrical rollers which absorb solar energy and are subsequently transported to a vaporization chamber wherein they are exposed to sea water or other saline water.
U.S. Pat. No. 4,055,948 discloses a solar thermal-radiation absorption and conversion system. A transparent heat transfer fluid moves suspended particles through an exposure zone. This patent contemplates filling the entire space of the collector section with a liquid. As a result, undesired heat loss to the collector will exist through such liquid contact. In addition, the system of this disclosure remains vulnerable to undesired leakage, freezing, and evaporation.
There remains, therefore, a need for an efficient thermal collection system which will be economical to adopt and use, efficient in operation and avoid a number of the above-described problems.